A solid oxide fuel cell (SOFCs) is a type of fuel cell which reacts a fuel gas with an oxidant to generate DC electric current. SOFCs comprises an anode, an electrolyte and a cathode, and have been made from a variety of materials and in a variety of geometries. Fuel processing is required to render hydrocarbon fuels (such as propane, butane, etc.) suitable for SOFCs. For example, known designs for fuel processors include those done with a separate external reactor where a catalytic substrate processes a hydrocarbon fuel such as butane (C4H10), propane (C3H8) or diesel fuel (JP-8 or JET-A) to a suitable fuel gas such containing carbon monoxide (CO) and hydrogen (H2). CO and Hydrogen gas are then oxidized at an active area of a SOFC to carbon dioxide and water, with DC current generated. Non hydrocarbon fuels such as ammonia (NH3) can also be transformed into SOFC fuel using one or more catalytic reactions.
It has become desirable to make solid oxide fuel cells as light as possible so that they may serve as a portable power source. An external reactor is bulky and is accompanied with significant inefficiencies in transfer of hot processed fuel gas from the reactor to the active area of the fuel cell. U.S. Patent Publication 2003/0054215 to Doshi et al discloses a stack of fuel cell plates where a catalytic substrate is positioned within the plates and within a thermal enclosure. However, such stack designs are known to have problems with thermal cycling, they cannot be heated and cooled quickly, and extensive seals have to be used, including seals subjected to high thermal loading. Further, hot seals have to be used at locations inside the thermal enclosure, and hot seals are expensive. Addressing all of these problems makes such stacked plate designs relatively expensive. It would be desirable to provide a solid oxide fuel cell of a simple, and lightweight design which is also robust in construction and capable of withstanding thermal cycling.